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<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <script>
      class A {
        constructor(props) {
          console.log("a", props);
          this.props = props;
        }
      }
      class B extends A {
        constructor(props) {
          // 这里相当于调用了A的constructor
          super(props);
          console.log(props);
          console.log(this.props);
        }
      }
      new B({ a: "zs" });
    </script>
  </body>
</html>
